If you’ve watched even a bit of television in 2012, you’ve probably seen Bruce Mentzer’s handiwork.

Mentzer doesn’t create the spots — his specialty is figuring out when, where and how often they run. His firm, Mentzer Media Services, has purchased at least $75 million in commercial time, mostly with money raised by three groups that have taken campaign spending to stratospheric levels in an effort to unseat President Obama. They are Restore Our Future, the super PAC run by former Romney advisers; Americans for Prosperity, a nonprofit organization with close ties to the tea party movement and billionaire industrialists Charles and David Koch; and American Crossroads, advised by Republican strategist Karl Rove.

Their zeal has vaulted Mentzer, who keeps a percentage of the time’s purchase price, to the top of the small-but-critical campaign sub-specialty of media buying. He’s one beneficiary of the windfall 2012 has brought to Washington’s consultant class of ad makers, pollsters, direct mailers and social media gurus. Not to mention television stations grown flush from the premium rates they can charge super PACs and other independent groups for airtime.

Fueled by new rules allowing unlimited contributions from wealthy individuals, corporations and unions, spending on television advertising in local and national races could top $3 billion, according to Kantar Media/CMAG, the ad tracking firm.

“It’s a consultant’s dream, all the money that’s on the table,” Democratic National Committee co-chairwoman Donna Brazile said.

Mentzer, 49, who works not in Georgetown or Old Town, but from a three-story office building near a shopping mall in Towson, Md., has had a hand in proliferating some of the era’s best-known Republican ads. He declined multiple interview requests, saying in an e-mail: “We have simply been too busy this cycle for me to respond to all the requests we have received from the press.”

His team draws on consumer research, demography, polling and Nielsen ratings to essentially place bets on where to best reach targeted voters.

Take one week in Pittsburgh (Aug. 13 to 20), strategically important because stations there also reach portions of eastern Ohio. Mentzer’s firm bought $143,440 worth of time on behalf of Restore Our Future and Americans for Prosperity for 235 half-minute ads, according to station filings with the Federal Communications Commission. Most were clustered around local newscasts, with lower prices and audiences known to be rich in frequent voters. Four spots on KDKA’s 5 p.m. news, for example, went for $700 each. Because research shows that Republicans like sports events and crime procedurals, a lot of the dollars also went to single spots on pricier prime-time shows such as “The Mentalist,” where one 30-second ad cost $1,650 and “Hawaii Five-O” ($2,100).

More challenging is the continued fragmentation of audiences. The rise of niche cable channels and video-on-demand sites have made effective media buying a constantly moving target. It means, for instance, that reaching likely-to-vote independents in a critical media market might require mixing traditional buys with the right slots on the Golf and Weather channels or the Game Show Network.

Clients said Mentzer’s grasp of the new media world inspires confidence.

“It’s comforting to have Bruce in the room because he is so smart about what to do,” said Adam Goodman, a Florida-based Republican consultant who has used Mentzer for years in congressional and legislative campaigns. His father, Republican ad maker Robert Goodman, hired Mentzer out of college for his Baltimore agency. Mentzer opened his own firm in 1991.

Mentzer benefits significantly from his association with Larry McCarthy, the Republican media consultant who has produced some of the most compelling — and sometimes misleading — ads of the last two decades.

McCarthy, who did not return a phone message, is best known for the racially loaded Willie Horton ad that helped to undo Democratic presidential candidate Michael Dukakis in 1988. (Mentzer did not sell time for the spot; McCarthy produced it for an independent group.)

McCarthy, Mitt Romney’s ad maker in 2008, now creates spots for the pro-Romney Restore our Future as well as Americans for Prosperity and American Crossroads.

Mentzer placed his work for Restore Our Future all over the primary season map, pummeling Rick Santorum from Michigan to Alabama as a big spender and Washington insider, and slamming Newt Gingrich in Iowa, South Carolina and Florida for ethical “baggage.”

Fact checkers had issues with some of the ads. But with two months until Election Day, and a constellation of big-spending groups committed to defeating Obama, Mentzer will continue his lucrative search for pockets of airtime that might be used to pick up a vote.